Cylinder-grinding tool



arch 23 1926., 1,577,811

I G. H. BLETTNER v CYLINDER GRINDING TOOL Filed Sept. 2, 1922 2 Sheets-Sheet 1 l o l 4.

50/5975 f/BLE TIA/1? Man-ch 23 G. H. BLETTNER CYLINDER GRINDING TOOL 2 Sheets-Sheet Filed Sept. 2, 1922 Patented Mar. 23, I

UNITED STATES 1,577,681 PATENT OFFICE.

enoaon n. BLETTNER, or onroae 'nnmors.

onmnnn-enmnme root.

Application filed September 2, 1922. Serial No. 585,880.

following is a full, clear, and exact descrip-- tion of the same, reference being had to the accompanying drawings, and'to the numerals of reference marked thereon, which form a part of this specification.

The refinishing of the interior surfaces of engine cylinders has'heretofore been an expensive matter, calling for a large shop with elaborate equipment.

It is the object of this invention to provide .a means for grinding the interior of engine cylinders to a true cylindrical surface without the need of any elaborate or expensive equipment and without the need of any careful placing of the cylinder upon the machine; a

It is a further object of this invention. to provide a tool which shall automatically center itself within the cylinder to be ground and shall produce a true cylindrical surface.

It is a further object of this invention to provide an improved means for securing the abrasive substance to the working surface of the tool.

It is a further object of this invention to' provide means for producing a uniform disground.

It is a further object of this invention to provide aresilient means for pressing the abradin'g tool against the surface of the cylinder.

It is a further object of this invention to provide such connections between the resilient means and the several abrading tools that the proper pressure will be applied to each tool.

It is a further object of this invention to provide a grinding means for cylinders which shall not contact with the inner surface of the cylinder at the bottom of scored places but shall confine its cutting action to the portions of the walls above such scored places.

Other and further important objects of this invention will be apparent from the disclosures in the drawings and specification.

The invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings: Figure 1 is a top plan View, and Figure 2 is a side elevation of the tool..

Figure 3 is a section upon the line of Figure 2.v

Figure 4 is'a section'- upon the broken line 4--4 of Figure 1.

Figure 5 is a bottom lower. end of. the tool.

As shownon the drawings:

A driving shaft 10 is connected to the driven shaft 11 of the tool by two joints 12 to enable the shaft '11 to-be rotated by the plan view of the shaft 10 and yet to be freely displaced 'lat- .erallyin any direction. Mounted upon the;

shaft 11 is a carrier 13, the upper part of I which as shown at 14 is enlargedto constitute a spring barrel. A fiat spiral spring 15 is coiled within this barrel, one endof it being secured to the barrel as shown at 16 and the other end of it being secured to the tends through the rabbet into a plate 22 suitably mounted upon the shaft 11 between the cover 18 and the barrel 14. One portion of the edge of the plate 22 is provided with teeth 23 which act as a worm wheel meshingwith the screw 24 which is mounted in bearings 25 supported ina; bracket 26 secured to the side of the barrel 14. At one end the screw 24 is provided with a'slot 27 for the reception of a screw driver or similar tool.

y The carrier 13 hasthree pairs of lugs 30'.

arranged in three radial directions, one pair in each direction, to accommodate three shafts 31 parallel to the shaft 11. Each shaft 31 protrudes through its pair of lugs 30 and engages the arms of a U-shaped carrier 32. Each of-these carriers has a pair of horizontal arms engagingthe shafts 'just .described and a vertical connecting piece 33.

Secured to the vertical portion 33 by means of dove-tailed joints 34 is a strip of abrasive material 35. The abrasive material may be of any desired kind, but I prefer to prepare it by introducing carborundum into fused lead and casting the mixturein moulds of the required form. The cutting face of this strip of abrasive material is crossed by oblique slots 36 as shown'in Figure 2.

Extending inward from each of the Vertical parts 33 of the arms 32, is a web' 37 and wound around each of' the shafts 31 is ,a spring 38, one end of which is anchored in one of the lugs and the other end of which bears against the corresponding web 37. The pressure of these springs tends to cause the arms 32 to move about the shaft 31 in such a direction that the strips 35 move counterelockwise as seen in Figure 1, or

clockwise as seen in Figure 5. The shaft 11 where it extends below the carrier 13 has pinned to it a triangular cam piece 40. In one extreme position of this triangular cam .piece, the action of the spring 15, which tends to move the cam 4.0 counterclockwise as seen in Fig. 5, presses the sides of the cam a ainst the s des of the arms 32 close to the .plvoted-ends of these arms so that the thlck ness of the arm whereit surrounds the pin 31 acts as a stop to limit the movement of the cam 40in this direction. This extreme position is illustrated in fulllines inFigure 5. In the o posite extreme positlon the .straight portions of the arms 32 come against the straight sides of the cam. piece 40. as'illustratedin dotted lines in Figure 5. The action of the springs 38 keeps the arms 32 against the sides of the cam 40 as it moves toward dotted line position. When the cam' arrives at this position the hubs of the arms 32 again act to afford a stop, preventing further movement of the cam 40 clockwise as seen in Figure 5. For conven ience in manipulatingthe tool a pair of recesses to receive the ends of a spanner wrench are provided in the cover 18 as shown at 42, and a similar pair of holes to receive the ends of a spanner wrench are provided in the barrel 14, one of these being shown at 43.

. mentioned limits is however governed by the range of movement of the pin 21 along the rabbet 20. It is possible to adjust the disks 22 to vary the arcuate travel of the pin 21 and hence the relative movement between the shaft 11 and the carrier 13. Thus the outward travel of the arms 32 may be controlled for any size cylinder between the limits of the maximum relative movement of the shaft 11 and carrier 13.

the one shaft 11.

newest Inthe use of the device, the. disk 22 may be first adjusted to regulate the device for the proper sized completed cylinder, a spanner wrench may then be applied to the holes 42 for moving the cover 18, and a second spanner wrench to the holes 43 for moving the barrel 14. These two are then moved in opposite directions so that the shaft 11 isrotated by the cover plate 18 relative to the barrel 14 and causes the spring 15 to wind up. This motion also causes the cam 40 to move clockwise in Figure 5 so that the edges of the cam tend to depart from the arms 32, but the springs 38 acting against the webs 37 cause the arms 32 to follow the.

cam in its movement towards the dotted position. 7

By comparing the full line position of the arms 32 with the dotted line position of them in Figure 5 it will be seen that the abrading surfaces 35 are nearer the center in the dotted line position than in the full line posi tion. Consequently the movement of the two spanner wrenches just described will cause the effective diameter of the tool to be less so that the tool may be introduced into an engine cylinder. "When the tool has thus been introduced, the spanner wrenches are released and the spring 15 moves the shaft 11 counterclockwise as seen in Figure 5 so that the edges of the cam 40 press against the arms 32-and move theinfrom the dotted line position towards the full line position. This causes the abrasive members 35 to spread out and contact with the walls of the cylinder.

It will be observed that each of the abrasive members moves out the same. distance, being all moved by the movement of The result is that the abrasive members 35 press equally against three lines of contact withthe cylinder and so move the tool until the center of the shaft 11 corresponds to the center of the cylinder as determined from these three lines of contact.

- Power is then applied to the shaft 10 to rotate the shaft 11 and cause the tool to rotate within the cylinder.

As long as the cylinder is truly round, and

ill)

the shaft 11 is at its center, this pressure will be equal at all of the members 35. In using the tool upon a worn cylinder, in which the contour is usually irregular, the pressure of'the three members 35 brings the shaft 11 to the center of the-circle determined by the three lines with which the three members 35 contact. As the tool rotates, one of these members will reach a place where the cylinder is of somewhat larger radius. The pressure of this member against'that side of the'cylinder will therefore diminish, but the action of the spring 15 in maintaining the cam 40 against the arms 32 tends to equalize the pressure on all three of the members 35. There will be a tendency to move the member which has found a side of larger radius toward that side. As far as this tendency is represented by an increase in the radial outward movement, it is shared by all three members 35,

for they are pressed out equally by the ac tion of the spring 15 and thetorque of the shaft 11 acting through the cam 40. There is, howeverfsome tendency for the tool to move sidewise toward the side, of. the cylinder having a larger radius, and this tendency has a part in equalizin the pressure/when the same has been ren ered unequal by an irregularity in the shape of the cylinder.

The inertia of the tool as a whole is considerable, for the tool is fairly heavy, and

the changes in pressure just discussed are small. Moreover, the time during which any one member tends to .move toward any one side of the cylinder is brief. The result is that the abrasive action of the tool does not reach the bottom of a low spot inthe cylinder, or, at most, touches it very lightly, until the cylinder as a whole has been enlarged sufficiently so that the new (correct) cylindrical surface .reachesto the.

bottomof the low spot. I

If he cyli der ossesses a side where the radius is smaller t an for'the. cylinderas a whole, the reverse action takes place, When an abrasive member 35 reaches sucha spot, the pressure of the cylinder wall 'agamst this member increases and tends to move the' arms 32 inward. This tendency is resisted by the pressure of the cam 40 against-the arm which has behind it the driving torque.

of the shaft 11, and this pressurejs combined with the action of the sprmg 15, which holds the inner endsyoftheiirms-in close contact with the sides lot the cams,' It-risfithere fore diflicult for'the,cylinderflwall topress;

the arms 35 inwardlyConsequently, when an abrasive member 35 meets a high spot in the cylinder wall, the pressure is materially increased and the grinding action is there'- fore greater at such a high spot. -Even1ft he high spot should press against the abrasive member 35 enough to move it inward in spite of the resistance afi'orded by .theitorque of the shaft 11 in the actionr of the spring 15 as just pointed out, there would result very little sidewise motionof the shaft 11,

if any, because although inwardmption one of the arms 32 is necessarily accentpanied by inward motionoftheothers, such motion is, as has just. been pointed;- out,

strongly resisted, and, moreover, the duration of the extra pressure against'any one abrasive-member is short, and the inertia of the tool is large. :5; f

As the grinding actio of the abrasive members enlarges the cylihdenthe force of the spring 15 tending to move the arms '32 outward, causes the grinding members to scored place, will not cause any sidewise motion, of the tool, and the bottom of such a local low point will not be cut at all, unless the cylinder as a whole is enlarged suificientlyto reach to said'botto-m. It should be borne in'mind that the chan es' in ra-" dius mentioned in thepreceding iscussions are seldom more than one or two hundredths of an inch, and frequently are smaller than this, so that'the change in the position of the axis of the cylinder reduced by the regrinding isusually on yfaj few thousandths of an inch. Usually this displacement of the axis" is in a direction to change the cylinder spacing of the engine,-but as this cylinder spacing :is ordinarily several inches, the

change in question is proportionately 450 J .the' character of the engine.

small that itmakes no noticeable change-in During the grinding action the slots 36in the; abrasive membcrs35 causethe lubricant wh ch is introduced into the-cylinder to flow upward; Between the abrasive members,

the lubricant drains downward over the sur face of the cylinder and it is again raised-by the grooves 36 in the next cutter as. the tool rotates. Asa result a continual flow of lui briant over the cylinder-surface isobtained so that'the cut'material is rapidly, carried away and thesurface kept in proper conditionfor grinding Ifthe cylinder is placed on'th'e bed of the drill press or other machine tool on which this instrument is used in a position which is not carefully centered. with respect to. the shaftr 0,.-the joints 12 enable the shaft 11 to align i. selfwith the axis of the cylinder and the cutters work correctlyeven though the cylinder is materially out of alignment with the shaft 10. Also the action just described I takesiplace equally wellin spite 'of this ofl'set because the pressure ofthecutters against i-tl ieficylinder depends not uponthe torque exerted by; the shaft 10 or the alignment with that shaft,fbutupon the tension in the spring 15. Therefore a truly cylindrical engine cylinder can be madewitliout carefully centering .the engine cylinder upon the machine tool. For the same reason it is-not necessary to hold the engine cylinder in place'upbn them-achine tool-by strapping it down or'jby; any, other strong fastening.

Ordinarily it is sufficient for the workman to hold the cylinder in place with his hand.

- newing cylinders with far less skilled workmen than are required by former methods,

and the expense of the operationof regrinding cylinders is materially reduced.

' I am aware that numerous details of construction may be varied through a wide range Without departing from the spirit of this invention, and I therefore do not purpose limiting myself further than is necessitated by the prior art.

I claim as my invention:

1. In a device of the class described, a carrier, a driving shaft upon which said car'- rier is rotatably mounted, a barrelrigid with said carrier, a spiral spring, one end of which is attached to said barrel and the other end of which is attached to said shaft, a cover for said barrel rigid with said shaft, means upon the barrel and cover for affording a grasp whereby the cover and barrel .may be grasped andmoved relative to one another for winding said spring.

2. In a device of the class described, a car rier, a driving shaft upon which said carrier is rotatably mounted, at barrel rigid with said carrier, a spiral spring, one end of which is attached to said barrel and the other end of which is attached to said shaft, a cover for said barrel rigid with said shaft, means upon the barrel and cover for afi'ording a grasp whereby the'cover and barrel may be grasped and moved relative to one another for winding said spring, abrading members movably mounted upon said carrier, and means actuated by the rotation of said carrier relative to said shaft for movmg said abrading members outward and inward, the inward motion occurring when said spring is Wound, whereby the relative motion afforded by said grasping means moves said carr ers radlally inward to per-.

mit the introduction of the device into a cylinder.

In a device of the class described, a carrier, a plurality of. arms pivotally mounted upon said carrier, a cam having straight sides adapted in one position to contact said arms at points distant from said pivots, the motion of the cam towards the last named position being limited by contact of said in the other extreme position to contact the circular hub portions of the adjacent arms, spring means tending to move said arms to the position in which their side portions will contact with the sides of the polygonal cam and when the latter is in the last named position will simultaneously move all of said arms against the action of their several springs.

' 5. In a device of the class described, a carrier having a plurality of lugs arranged in pairs, each pair extendingradially, abrasive carrying arms pivotally mounted, one

in each pair of said lugs, said arms having circular hub'portions surrounding their pivots and side'portions tangential to the circular portion, a, polygonal cam-mounted in said carrier, and adapted in one position to contact the sides of said arms and in the other positionto contact the circular hub portions of the adjacent arms, spring means tending to move said arms to the position in which their sides will contact with the sides of the polygonal cam when the latter is in the last named position, whereby rotating the cam away from the last named position willsimultaneously move all of said arms against the action of their several springs, and spring means for rotating said polygonal cam in the direction to accomplish said last named motion.

6. In a cylinder grinding machine, driving shaft, a sleeve member loosely mounted upon said shaft, 'a yielding connection be'-' tween said shaft and sleeve, abradant members pivotally mounted upon said sleeve member for swinging movement, a device secured upon said shaft for engagement with said abrasive members to project the same and toward which device saidyielding connection urges said members ,said shaft havsaid sleeve member, and means for varying such limited relative rotarymovement.

7. In a cylinder grinding machine, a driving shaft, a sleeve member connected to said shaft for limited relative rotary movement, an adjustable member carried by said sleeve for varying such relative rotary movement, abradant members hinged to said sleeve member for swinging movement, a driving .devlce on said shaft for engaging said abradant members to project them, and yielding means relatively urging the device and 7 members into projecting relation.

8. In a cylinder grinding machine, a driying shaft, a sleeve loosely mounted upon said shaft, a yielding connection between said sleeve and shaft, a plurality of abradant members hinged-to said sleeve, a device upon said shaft for engaging said abradant members to project them, and having relative movement with respect thereto, said yielding connection relatively urging the device and members into projecting relation.

mg a limited relative rotary movement to Hit ieo

9. In a cylinder grinding machine, a shaft, a sleeve loosely mounted upon said shaft, :1 yielding connection between said sleeve and shaft, positive means for providing a predetermined relative rotary movement between said sleeve and shaft, abradant members pivotally mounted upon said sleeve, and a cam device on said shaft for engaging said abradant members to project them, said yielding connection relatively urging the device and members into projecting relation.

10. In a cylinder grinding machine, a

shaft, a sleeve member loosely mounted upon said shaft, an adjustable-connection between said sleeve member and shaft providing a predetermined relative rotation,- abradant members hinged upon said sleeve and a cam device upon said shaft adapted for driving relation With said abradant members, and yielding means relatively urging the device and members into projecting relation.

In testimony whereof I have hereunto sub scribed my name.

GEORGE BLETTNER. 

